It started with a kick to the head. Then a wicked three-punch combo and soon another powerful kick, then a right cross, then a crushing upper cut and then finally an absolutely vicious knee to the face.

Chris Leben had entered the Ultimate Fighting Championship’s caged octagon in June 2006 boasting a promising future, a 15-1 record and a granite chin. Forty-nine seconds later he was knocked out by Anderson Silva.

The Brazilian, making his UFC debut, had unleashed an explosion of violence so impressive it managed to shock a sport built on explosions of violence.

“I must have said Holy (expletive) 15 times in 49 seconds,” said Dana White, the UFC president.